FontDirs is a slice of directories searched for font data files.
If the first font file found is unreadable or cannot be parsed, then
subsequent directories are not tried, and the font will fail to load.

The default slice is initialised with the contents of the VGFONTPATH
environment variable if it is defined.
This slice may be changed to load fonts from different locations.

type Canvas interface {
// SetLineWidth sets the width of stroked paths.
// If the width is not positive then stroked lines
// are not drawn.
//
// The initial line width is 1 point.SetLineWidth(Length)
// SetLineDash sets the dash pattern for lines.
// The pattern slice specifies the lengths of
// alternating dashes and gaps, and the offset
// specifies the distance into the dash pattern
// to start the dash.
//
// The initial dash pattern is a solid line.SetLineDash(pattern []Length, offset Length)
// SetColor sets the current drawing color.
// Note that fill color and stroke color are
// the same, so if you want different fill
// and stroke colors then you must set a color,
// draw fills, set a new color and then draw lines.
//
// The initial color is black.
// If SetColor is called with a nil color then black is used.SetColor(color.Color)
// Rotate applies a rotation transform to the context.
// The parameter is specified in radians.Rotate(rad float64)
// Translate applies a translational transform
// to the context.Translate(pt Point)
// Scale applies a scaling transform to the
// context.Scale(x, y float64)
// Push saves the current line width, the
// current dash pattern, the current
// transforms, and the current color
// onto a stack so that the state can later
// be restored by calling Pop().Push()
// Pop restores the context saved by the
// corresponding call to Push().Pop()
// Stroke strokes the given path.Stroke(Path)
// Fill fills the given path.Fill(Path)
// FillString fills in text at the specified
// location using the given font.
// If the font size is zero, the text is not drawn.FillString(f Font, pt Point, text string)
// DrawImage draws the image, scaled to fit
// the destination rectangle.DrawImage(rect Rectangle, img image.Image)
}

A Canvas is the main drawing interface for 2D vector
graphics.
The origin is in the bottom left corner.

type Font struct {
// Size is the size of the font. The font size can
// be used as a reasonable value for the vertical
// distance between two successive lines of text.SizeLength// contains filtered or unexported fields
}

MakeFont returns a font object. The name of the font must
be a key of the FontMap. The font file is located by searching
the FontDirs slice for a directory containing the relevant font
file. The font file name is name mapped by FontMap with the
.ttf extension. For example, the font file for the font name
Courier is LiberationMono-Regular.ttf.

type FontExtents struct {
// Ascent is the distance that the text
// extends above the baseline.AscentLength// Descent is the distance that the text
// extends below the baseline. The descent
// is given as a negative value.DescentLength// Height is the distance from the lowest
// descending point to the highest ascending
// point.HeightLength
}

ParseLength parses a Length string.
A Length string is a possible signed floating number with a unit.
e.g. "42cm" "2.4in" "66pt"
If no unit was given, ParseLength assumes it was (postscript) points.
Currently valid units are:

type PathComp struct {
// Type is the type of a particluar component.
// Based on the type, each of the following
// fields may have a different meaning or may
// be meaningless.Typeint// The Pos field is used as the destination
// of a MoveComp or LineComp and is the center
// point of an ArcComp. It is not used in
// the CloseComp.PosPoint// Control is one or two intermediate points
// for a CurveComp used by QuadTo and CubeTo.Control []Point// Radius is only used for ArcComps, it is
// the radius of the circle defining the arc.RadiusLength// Start and Angle are only used for ArcComps.
// They define the start angle and sweep angle of
// the arc around the circle. The units of the
// angle are radians.Start, Anglefloat64
}